The demolition of concrete structures and highway reconstruction can present significant problems in the disposal of large pieces of concrete including reinforced concrete and concrete paving. For example the disposal of large concrete slabs and large reinforced concrete structures can be difficult. One solution to the disposal of such concrete pieces is the use of a crusher or pulverizer which can break large concrete pieces into smaller particle sizes and chunks. By breaking the concrete up, one may be able to reuse the concrete as fill or as an aggregate base for roadways and other construction sites.
Concrete processors used for demolition can be broken into two broad categories of crushing equipment. The first category consists of primary processors which can be good for the demolition of concrete and precast structures. These processors which are designed for controlled demolition are able to deliver force to a small surface area using high pressure which results in clean, precise cracks. Such processors can also be used as a secondary concrete crusher for recycling. The second category of concrete processors is mainly used for secondary breaking of reinforced concrete. These processors can break concrete into further fines for recycling and they can be used to separate concrete from rebar. Such processors are able to deliver force over multiple points and this process causes the concrete to crumble. These processors can be attached to the dipper arm of a power excavator as an attachment which replaces the usual bucket used for digging.
A particular form of concrete pulverizer that can be referred to as a mechanical pulverizer is adapted for attachment to the outer or front end of the dipper arm of an excavator and this pulverizer uses the existing bucket cylinder mounted on the dipper arm to pulverize or crush the concrete piece by means of a jaw or tool connected to the hydraulic cylinder actuator. An advantage of a pulverizer of this type is that it is faster to operate and it can be less expensive than a hydraulically operated pulverizer that employs its own hydraulic cylinder or cylinders for the pulverizing operation.
One known form of mechanical pulverizer is taught in U.S. Pat. No. 6,129,298 issued Oct. 10, 2000 to National Attachments, Inc. This known pulverizer is mounted on the outer end of the dipper arm of an excavator and it includes two jaws confronting and closing on one another and an independent ripper-shank with a ripper tooth. Each jaw includes teeth that serve to engage and fracture concrete slabs. One of the jaws can be pivoted by the large hydraulic cylinder actuator mounted on the front side of the dipper arm or dipper stick. The pulverizer/ripper unit is pivotably attached at 3 points at the end of the dipper stick. Each of the two jaw sections includes multiple projections in the form of upper and lower teeth with a working gap located these two sets of teeth.
There is a need for an improved mechanical-type pulverizer that is better able to pickup chunks of concrete and that is better able to position each large chunk closer to the pivot axis of the jaws of the pulverizer so that a better crushing force can be applied to the concrete piece.